df4390934d
XArrays are a better match than IDR for how AppArmor is mapping secids. Specifically AppArmor is trying to keep the allocation dense. XArrays also have the advantage of avoiding the complexity IDRs preallocation. In addition this avoids/fixes a lockdep issue raised in the LKML thread "Linux 5.18-rc4" where there is a report of an interaction between apparmor and IPC, this warning may have been spurious as the reported issue is in a per-cpu local lock taken by the IDR. With the one side in the IPC id allocation and the other in AppArmor's secid allocation. Description by John Johansen <john.johansen@canonical.com> Message-Id: <226cee6a-6ca1-b603-db08-8500cd8f77b7@gnuweeb.org> Signed-off-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: John Johansen <john.johansen@canonical.com>
146 lines
3.2 KiB
C
146 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* AppArmor security module
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*
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* This file contains AppArmor security identifier (secid) manipulation fns
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*
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* Copyright 2009-2017 Canonical Ltd.
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*
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* AppArmor allocates a unique secid for every label used. If a label
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* is replaced it receives the secid of the label it is replacing.
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*/
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#include <linux/errno.h>
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#include <linux/err.h>
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#include <linux/gfp.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/xarray.h>
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#include "include/cred.h"
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#include "include/lib.h"
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#include "include/secid.h"
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#include "include/label.h"
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#include "include/policy_ns.h"
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/*
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* secids - do not pin labels with a refcount. They rely on the label
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* properly updating/freeing them
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*/
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#define AA_FIRST_SECID 2
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static DEFINE_XARRAY_FLAGS(aa_secids, XA_FLAGS_LOCK_IRQ | XA_FLAGS_TRACK_FREE);
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/*
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* TODO: allow policy to reserve a secid range?
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* TODO: add secid pinning
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* TODO: use secid_update in label replace
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*/
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/**
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* aa_secid_update - update a secid mapping to a new label
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* @secid: secid to update
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* @label: label the secid will now map to
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*/
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void aa_secid_update(u32 secid, struct aa_label *label)
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{
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unsigned long flags;
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xa_lock_irqsave(&aa_secids, flags);
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__xa_store(&aa_secids, secid, label, 0);
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xa_unlock_irqrestore(&aa_secids, flags);
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}
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/**
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*
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* see label for inverse aa_label_to_secid
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*/
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struct aa_label *aa_secid_to_label(u32 secid)
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{
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return xa_load(&aa_secids, secid);
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}
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int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
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{
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/* TODO: cache secctx and ref count so we don't have to recreate */
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struct aa_label *label = aa_secid_to_label(secid);
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int len;
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AA_BUG(!seclen);
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if (!label)
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return -EINVAL;
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if (secdata)
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len = aa_label_asxprint(secdata, root_ns, label,
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FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
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FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT,
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GFP_ATOMIC);
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else
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len = aa_label_snxprint(NULL, 0, root_ns, label,
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FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
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FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT);
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if (len < 0)
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return -ENOMEM;
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*seclen = len;
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return 0;
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}
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int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
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{
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struct aa_label *label;
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label = aa_label_strn_parse(&root_ns->unconfined->label, secdata,
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seclen, GFP_KERNEL, false, false);
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if (IS_ERR(label))
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return PTR_ERR(label);
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*secid = label->secid;
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return 0;
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}
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void apparmor_release_secctx(char *secdata, u32 seclen)
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{
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kfree(secdata);
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}
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/**
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* aa_alloc_secid - allocate a new secid for a profile
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* @label: the label to allocate a secid for
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* @gfp: memory allocation flags
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*
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* Returns: 0 with @label->secid initialized
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* <0 returns error with @label->secid set to AA_SECID_INVALID
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*/
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int aa_alloc_secid(struct aa_label *label, gfp_t gfp)
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{
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unsigned long flags;
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int ret;
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xa_lock_irqsave(&aa_secids, flags);
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ret = __xa_alloc(&aa_secids, &label->secid, label,
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XA_LIMIT(AA_FIRST_SECID, INT_MAX), gfp);
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xa_unlock_irqrestore(&aa_secids, flags);
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if (ret < 0) {
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label->secid = AA_SECID_INVALID;
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return ret;
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}
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return 0;
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}
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/**
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* aa_free_secid - free a secid
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* @secid: secid to free
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*/
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void aa_free_secid(u32 secid)
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{
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unsigned long flags;
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xa_lock_irqsave(&aa_secids, flags);
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__xa_erase(&aa_secids, secid);
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xa_unlock_irqrestore(&aa_secids, flags);
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}
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